More detail

Scenario: If developer A is working on ticket 1 and developer B is working on ticket 2 and writes some notes (on ticket 2) how it’s related to ticket 1, it automatically makes a (ticket-2)-to-(ticket 1) link that’s easy to follow to get more details. So far so good. However, developer A has no idea her ticket has just been discussed on ticket 2, and tinkers on blithely unaware of what is going on around her, because there is no reciprocal (ticket 1)-to-(ticket 2) link.

How can we automatically indicate that tickets are being discussed at other tickets? TracBacks. What this plugin does is simply to create that reciprocal (ticket 1)-to-(ticket 2) link so that anyone looking at ticket 1 can see it has been talked about on ticket 2 as well.

ticket.get_changelog() returns entries that aren't comments (as well as entries that are comments) -- so, if the latest modification on the ticket does not have a comment, tracbacks will cause an internal error by assuming an incorrect data structure. this commit fixes the problem by filtering out all changelog entries that are not comments. (fixes #9743)